As the light not only reflects from transparent objects but also passes through them, making the 3D measurements of transparent materials like glass and acrylic leads to the problem of multi-reflection. For this reason, making the 3D measurements of transparent objects gets difficult. Therefore in measurement of the objects' surfaces with imaging systems, the opaque objects are being focused on in general, not the transparent objects. The surface measurements of the objects which reflect the light can be carried out by the methods of photometric stereo or coloured photometric stereo which can make shaping by means of shading. Whereas a new method reflects the light band to the transparent object and calculates the surface shape of the transparent object by using a generic algorithm. Polarization is another useful method in calculating the shape of the transparent objects. However the said methods can operate under special conditions and they are quite slow to be able to make real-time 3D modeling on production line and to be used in quality control.
In U.S. Pat. No. 6,367,968 within the state of the art, a system which is used to make measurement and controls on the surfaces of the objects by utilizing infrared thermography is mentioned. In said method, focal-plane array cameras are used as well. The apparatus which is mentioned in U.S. Pat. No. 6,367,968 determines changes taken place in the thickness of the object which has become thin. In said document by using a lamp, a particular region is heated in an equal distribution. Then the temperature distribution in the course of time is examined by the method of FFT (Fast Fourier Transform) and as the temperature distribution is different in regions which are thinner or thicker than normal, these regions are determined. As is seen, any 3D) modeling is not made in said document, only errors are measured from surface roughnesses by using thermography method.
Documents DE10006663A1, U.S. Pat. No. 6,128,086, JP63061107, US2007/0271064A 1 and EP0007227 describe applications which observe the reflected light off the surface of the objects and process them to obtain information about the surface shapes.